1353944Sdim//===-- xray_init.cpp -------------------------------------------*- C++ -*-===// 2353944Sdim// 3353944Sdim// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4353944Sdim// See https://llvm.org/LICENSE.txt for license information. 5353944Sdim// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6353944Sdim// 7353944Sdim//===----------------------------------------------------------------------===// 8353944Sdim// 9353944Sdim// This file is a part of XRay, a dynamic runtime instrumentation system. 10353944Sdim// 11353944Sdim// XRay initialisation logic. 12353944Sdim//===----------------------------------------------------------------------===// 13353944Sdim 14353944Sdim#include <fcntl.h> 15353944Sdim#include <strings.h> 16353944Sdim#include <unistd.h> 17353944Sdim 18353944Sdim#include "sanitizer_common/sanitizer_common.h" 19353944Sdim#include "xray_defs.h" 20353944Sdim#include "xray_flags.h" 21353944Sdim#include "xray_interface_internal.h" 22353944Sdim 23353944Sdimextern "C" { 24353944Sdimvoid __xray_init(); 25353944Sdimextern const XRaySledEntry __start_xray_instr_map[] __attribute__((weak)); 26353944Sdimextern const XRaySledEntry __stop_xray_instr_map[] __attribute__((weak)); 27353944Sdimextern const XRayFunctionSledIndex __start_xray_fn_idx[] __attribute__((weak)); 28353944Sdimextern const XRayFunctionSledIndex __stop_xray_fn_idx[] __attribute__((weak)); 29353944Sdim 30353944Sdim#if SANITIZER_MAC 31353944Sdim// HACK: This is a temporary workaround to make XRay build on 32353944Sdim// Darwin, but it will probably not work at runtime. 33353944Sdimconst XRaySledEntry __start_xray_instr_map[] = {}; 34353944Sdimextern const XRaySledEntry __stop_xray_instr_map[] = {}; 35353944Sdimextern const XRayFunctionSledIndex __start_xray_fn_idx[] = {}; 36353944Sdimextern const XRayFunctionSledIndex __stop_xray_fn_idx[] = {}; 37353944Sdim#endif 38353944Sdim} 39353944Sdim 40353944Sdimusing namespace __xray; 41353944Sdim 42353944Sdim// When set to 'true' this means the XRay runtime has been initialised. We use 43353944Sdim// the weak symbols defined above (__start_xray_inst_map and 44353944Sdim// __stop_xray_instr_map) to initialise the instrumentation map that XRay uses 45353944Sdim// for runtime patching/unpatching of instrumentation points. 46353944Sdim// 47353944Sdim// FIXME: Support DSO instrumentation maps too. The current solution only works 48353944Sdim// for statically linked executables. 49353944Sdimatomic_uint8_t XRayInitialized{0}; 50353944Sdim 51353944Sdim// This should always be updated before XRayInitialized is updated. 52353944SdimSpinMutex XRayInstrMapMutex; 53353944SdimXRaySledMap XRayInstrMap; 54353944Sdim 55353944Sdim// Global flag to determine whether the flags have been initialized. 56353944Sdimatomic_uint8_t XRayFlagsInitialized{0}; 57353944Sdim 58353944Sdim// A mutex to allow only one thread to initialize the XRay data structures. 59353944SdimSpinMutex XRayInitMutex; 60353944Sdim 61353944Sdim// __xray_init() will do the actual loading of the current process' memory map 62353944Sdim// and then proceed to look for the .xray_instr_map section/segment. 63353944Sdimvoid __xray_init() XRAY_NEVER_INSTRUMENT { 64353944Sdim SpinMutexLock Guard(&XRayInitMutex); 65353944Sdim // Short-circuit if we've already initialized XRay before. 66353944Sdim if (atomic_load(&XRayInitialized, memory_order_acquire)) 67353944Sdim return; 68353944Sdim 69353944Sdim // XRAY is not compatible with PaX MPROTECT 70353944Sdim CheckMPROTECT(); 71353944Sdim 72353944Sdim if (!atomic_load(&XRayFlagsInitialized, memory_order_acquire)) { 73353944Sdim initializeFlags(); 74353944Sdim atomic_store(&XRayFlagsInitialized, true, memory_order_release); 75353944Sdim } 76353944Sdim 77353944Sdim if (__start_xray_instr_map == nullptr) { 78353944Sdim if (Verbosity()) 79353944Sdim Report("XRay instrumentation map missing. Not initializing XRay.\n"); 80353944Sdim return; 81353944Sdim } 82353944Sdim 83353944Sdim { 84353944Sdim SpinMutexLock Guard(&XRayInstrMapMutex); 85353944Sdim XRayInstrMap.Sleds = __start_xray_instr_map; 86353944Sdim XRayInstrMap.Entries = __stop_xray_instr_map - __start_xray_instr_map; 87353944Sdim XRayInstrMap.SledsIndex = __start_xray_fn_idx; 88353944Sdim XRayInstrMap.Functions = __stop_xray_fn_idx - __start_xray_fn_idx; 89353944Sdim } 90353944Sdim atomic_store(&XRayInitialized, true, memory_order_release); 91353944Sdim 92353944Sdim#ifndef XRAY_NO_PREINIT 93353944Sdim if (flags()->patch_premain) 94353944Sdim __xray_patch(); 95353944Sdim#endif 96353944Sdim} 97353944Sdim 98353944Sdim// FIXME: Make check-xray tests work on FreeBSD without 99353944Sdim// SANITIZER_CAN_USE_PREINIT_ARRAY. 100353944Sdim// See sanitizer_internal_defs.h where the macro is defined. 101353944Sdim// Calling unresolved PLT functions in .preinit_array can lead to deadlock on 102353944Sdim// FreeBSD but here it seems benign. 103353944Sdim#if !defined(XRAY_NO_PREINIT) && \ 104353944Sdim (SANITIZER_CAN_USE_PREINIT_ARRAY || SANITIZER_FREEBSD) 105353944Sdim// Only add the preinit array initialization if the sanitizers can. 106353944Sdim__attribute__((section(".preinit_array"), 107353944Sdim used)) void (*__local_xray_preinit)(void) = __xray_init; 108353944Sdim#else 109353944Sdim// If we cannot use the .preinit_array section, we should instead use dynamic 110353944Sdim// initialisation. 111353944Sdim__attribute__ ((constructor (0))) 112353944Sdimstatic void __local_xray_dyninit() { 113353944Sdim __xray_init(); 114353944Sdim} 115353944Sdim#endif 116